Heretofore there have been various efforts made to insulate greenhouses, as by whitewashing the windows when it is desired to reflect light and heat therefrom, or to paint the greenhouse windows green to shade the contents of the greenhouse. Furthermore, most greenhouses as made today, especially commerical greenhouses, have arrangements for heating the greenhouse and its contents to facilitate growth of the plants contained therein. Such cost of heating the greenhouse is one of the larger cost factors in the expenses of producing crops or products in the greenhouse. Snow may collect on the greenhouse roof and hamper flow of heat and light into the greenhouse.
Heretofore, it has been proposed that greenhouses use some relatively inexpensive plastic sheets to form spaced inner and outer walls or surfaces for the greenhouse to provide relatively inexpensive enclosure means therefor. One illustration of such type of a unit is shown in U.S. Pat. No. 3,080,875.
However, greenhouses as made and used today do have costly problems in their heating and in maintaining flow of the sun's rays to the greehhouse and its contents.
The general object of the present invention is to provide novel and improved low cost insulating roof panels or units for greenhouses to insulate the same and to permit the sun's rays to flow through the insulation panel into the greenhouse to reach the contents thereof.
Another object of the invention is to build up insulation panels from transparent plastic members both in tube and sheet form to form a unit that can be secured to a greenhouse glass pane and form an insulative, protective barrier layer thereover, which panel unit preferably is air tight and includes a confined air mass therein.
Other objects of the invention are to provide hollow insulating cover units or panels for part of a greenhouse roof to substitute for glass panes; to provide carrier frames for plastic panel units; and to provide low cost durable insulation panels that fit into the metal frames of greenhouses.
Yet another object of the invention is to make up standard insulating panels for greenhouses and wherein plastic components form the outer portion of the panel that is completed by a standard glass panel which can be positioned in standard greenhouse frame means.
The foregoing and other objects and advantages of the invention will be made apparent as the specification proceeds.